Young cynomolgus monkeys Macaque cynomolgus that were inoculated intracerebrally (IC) with "Biken" strain of Subacute Sclerosing Panencephalitis (SSPE) virus were monitored. One animal has had frequent grand mal seizures for the last 12 months (one or two seizures per week). This animal exhibits measles antibody and oligoclonal bands in its sera and CSF. Several attempts have been made to infect patas monkeys Erythrocebus patas with human varicella (HU-ZV). All have been unsuccessful until we inoculated the virus directly into the dorsal root ganglion T7 area. At this time, the animal has developed high serum and CSF antibody titers to HU-ZV. A varicella-like virus, "Delta agents" readily infects patas monkeys and has been reported to become latent in the patas monkey. We have been able to activate a latent infection of Delta (DHV).